PORTLAND, Maine — Maine’s oldest and largest gay rights advocacy group has endorsed Democratic U.S. Rep. Mike Michaud in the state’s 2014 gubernatorial race, throwing its weight behind the six-term congressman who would become the nation’s first openly gay governor.

While EqualityMaine’s endorsement Thursday may seem like a given considering the potentially historic import of Michaud’s candidacy, the group also has strong links to independent candidate Eliot Cutler.

Cutler has been a major donor to EqualityMaine and its causes in the past. In 2009, he and his wife contributed $14,600 to efforts to uphold a law legalizing same-sex marriage, according to the Maine Ethics Commission.

Cutler’s campaign on Thursday dismissed the EqualityMaine endorsement as “a partisan political decision, not a principled one.” Cutler spokeswoman Crystal Canney issued a statement contrasting the independent’s history supporting gay rights with Michaud’s background on the issue.

“Eliot Cutler and his family have stood side by side with the [lesbian, gay, bisexual and transexual] community for decades as outspoken advocates and supporters. Mike Michaud’s voting record in the Maine Legislature — 19 consecutive votes against equal rights for the LGBT community — speaks for itself,” Canney said. “EqualityMaine cannot take away Eliot Cutler’s record on these issues, any more than they can create a new record for Mike Michaud.”

Michaud’s campaign has downplayed the lawmaker’s record in the Maine Legislature, saying he, like many politicians, has evolved on the issues over time. Staffers point to his record in D.C., where he has earned a near-perfect approval rating from the Human Rights Campaign for his votes on issues of LGBT equality.

David Farmer, a senior adviser with the Michaud campaign, told the Bangor Daily News on Thursday that the lawmaker co-sponsored the Employment Non-Discrimination Act and Respect for Marriage Act in the House, and joined other federal lawmakers in filing an amicus brief on the Defense of Marriage Act as it was being debated at the U.S. Supreme Court, among other high-profile stands in support of gay rights.

“Eliot Cutler’s response, I think, shows his true colors,” said Farmer. “He’s a Washington lawyer, and if he doesn’t get what he wants, he attacks. Cutler has been a prominent supporter [of gay rights causes] since 2009, and most of that has been financial. As someone who has worked on these campaigns, I can say those contributions are critically important, but … the record [Cutler] has doesn’t include any tough votes on the issues, ever.”

“Eliot Cutler has been a generous and outspoken supporter of LGBT rights since 2009 and we appreciate that support,” Vander Zanden said during a late morning Thursday news conference in Portland. “Since 1998, [Michaud] has been a stalwart supporter of equal rights for all Mainers … and we could not have asked for a better advocate in Congress.”

Vander Zanden said EqualityMaine hopes to revive the 8,000-plus volunteers it marshalled during the 2012 referendum campaign to legalize same-sex marriage to help push Michaud into the Blaine House.

Speaking as “a lesbian who grew up in a small Maine town,” she said the chance to elect an LGBT “role model” to such a prominent political office was too important to pass up.

As part of a Thursday morning news conference to announce the organization’s endorsement, other prominent LGBT advocates voiced support for Michaud, including Dale McCormick, former Maine State Housing Authority head and the first open-LGBT individual to be elected to the state Legislature, and former Portland city councilor Barb Wood, who three decades ago helped found the group that would become EqualityMaine.

“[T]his time around, not only are my core values of equality and choice most closely aligned with Cutler’s — a lifetime of being pro-equality and pro-choice — but his leadership strategies of building coalitions among all political affiliations are an extension of the work I’ve been doing for the last two decades and are critical for moving Maine forward,” Smith wrote in an commentary distributed to Maine media outlets at the time.

The only major candidate for whom an EqualityMaine endorsement would have seemed all but impossible was Republican incumbent Gov. Paul LePage, a conservative who attracted vocal opposition from the gay rights group during his successful run in 2010.

Brent Littlefield, LePage’s campaign strategist, did not directly address EqualityMaine’s endorsement of Michaud when asked for a comment.

“The governor’s focus is on creating jobs for all Mainers,” Littlefield wrote in an email to the BDN.

In 2010, Cutler overcame Democrat Libby Mitchell and came within a few percentage points of defeating LePage. Michaud is seen as a stronger candidate for the Democrats in 2014 than Mitchell was in 2010, but political observers say he will have to wrest votes from Cutler in the more liberal 1st Congressional District to prevent the Democrat and independent from splitting the 2014 moderate and liberal votes in a way that would deliver the election to LePage

In her morning statement, Canney pointed out that Cutler has hosted annual EqualityMaine awards dinners since 2010, and has helped raise tens of thousands of dollars for the organization and its campaigns in recent years. Conversely, she noted that Michaud on 19 occasions as a state legislator cast votes considered to be against gay rights, including multiple votes during the 1990s — most recently in 1997 — against bills aiming to expand anti-discrimination laws to protect the LGBT community.

But Farmer countered Thursday that Michaud since has become a staunch supporter of gay rights both in Maine and in Washington, D.C.

“I think like most Mainers, the congressman’s views on same-sex issues have evolved over time,” he said, adding that the successful 2012 marriage campaign counted on the fact that statewide voters, like Michaud, could “improve, change their minds and get better.”

In a statement released by the organization, Michaud welcomed the EqualityMaine endorsement.

“I’m deeply humbled by this endorsement. The efforts of EqualityMaine have truly changed hearts and minds, and made our state a better place for all Mainers to live, work and raise a family,” he said. “For years I have been honored to stand with EqualityMaine and other LGBT organizations as we’ve fought for full equality for all Maine people, and I will continue to stand with them as governor of Maine. Together we have made tremendous progress at the state and federal level, but there is still more work to be done.”